First-principles simulations for atto-second photoelectron spectroscopy based on time-dependent density functional theory

We develop a first-principles simulation method for atto-second time-resolved photoelectron spectroscopy. This method enables us to directly simulate the whole experimental processes, including excitation, emission and detection on equal footing. To examine the performance of the method, we use it to compute the reconstruction of atto-second beating by interference of two-photon transitions (RABBITT) experiments of gas-phase Argon. The computed RABBITT photoionization delay is in very good agreement with recent experimental results from [Kluender et al., Phys. Rev. Lett. 106, 143002 (2011)] and [Guenot et al., Phys. Rev. A 85, 053424 (2012)]. This indicates the significance of a fully-consistent theoretical treatment of the whole measurement process to properly describe experimental observables in atto-second photoelectron spectroscopy. The present framework opens the path to unravel the microscopic processes underlying RABBITT spectra in more complex materials and nano-structures. (authors)